Yep, that is right. They will get revenue from the house edge. Zero house edge which means high possible of scam or having shady services.
As far as I know, there is currently running a gambling dice site that has the lowest house edge on this forum, which is crypto-games.net. If I was not mistken that is 0.8% house edge. I prefer to use a gambling site that has a 1% house than using 0% house edge that high possibility of losing money.

Refer to this link for the dice gambling site's house edge, https://bitcointalk.org/index.php?topic=2097255.0